Pressure-casting apparatus



'March 9, 1937.

A. BAUER PRESSURE; CASTING APPARATUS Filed April 19, 1934 In vemor AL FRED BAUER. By Afforne y inconveniences. 7

placed without dismounting the latte'iz I 40 Patented Mae: 9, 1937 epNiTED ENT omen I with; i 4

signor, by mesne assignments, to'Magnesium Development Corporation, a corporation of Delaware I Application April 19, 1934 Serial No. 721,292 4 In Germany'April 26, 1933,

4 cla ms. (Cl.. 32-70) Y This invention relates to pressure-casting apparatus of the hydraulic plunger type and to 1 a method of operating 'such apparatus. When working with metalsof high melting 5 point in casting apparatus of 'theplung'er type in which the plungeris, in constant contact with e the molten metal when the apparatus is in use, certain drawbacksfrequently 'arise.- Thus, pn prolonged use, the plunger seizes in its guide sleeve and this becomes particularly troublesome when the seizing *occursg during, the delivery stroke of the plunger and the return thrust .of the hydraulic medium is insufiiciently powerful p to free the plunger an d force it back into its ini-' ;l 5 tial position. Another, inconvenience is that after prolonged use, the play between the plung er and the sleeve is gradually increased to such an extent that work can no longer be continued without prejudice to the quality of the castings:

Inboth cases'it is necessary to;' change the plunger',and this, in the case of apparatus in which the plunger is'directly, connected with the operating (hydraulic cylinder (that is,. without intermediate levers, plate connectors or the like) entails the-complete dismounting'pf the pressure Q the melting apparatus as well. t

The present'invention aims at obviating these" unit operating the plunger, and frequently of 3o To this end, the invention provides' in a pressure-casting apparatus of the typ'e'in which the plunger is in'contact with the molten metal,a constructior in which the plunger is actuated by a: cylinder located on the\pressure ;chaniber and th'e -hydraulic pressureis applied not direct- *ly to'the plunger but to lateral means attached; theret'o, thus enabling the plungerto be detached from the'taotuating'mechanism and re- By suitably designing .the Iateralmeans as difierential pistons, this arrangement also en ables the seized plunger to be withdrawn and lieplaced in any circumstances.

'In carrying out the invention, the plunger .45 may, "for eitample; bedetachably mounted (for example, by pwedging) in an annular piston on whichthe hydraulic force acts. I

In a particularly suitable embodiment of the invention, two pressure cylinders may be dis- 50 posed laterally'of the plunger and secured to its guide, said cylinders housing two pistons operating synchronously and under equahpressure and being connected to vthe worln'ng plunger by means of a cross-head. 55 This latter embodiment is illustrated by way unit on a pcsitiomthe working plunger a is situated in the pressure chamber -b, on which the hydraulic unit 'cds directly-mounted. Said unit a is provided witna central bore iorxthe 10 passage :of the .working plunger, on either side of which'are the two symmetrically disposed hydraulic cylinders d housing tons e of equal 'dim'ensions and connected bycans of piston rods 'e, in a rigid but detachable mannrtoi a cross- 15 head i which inturn' is connected to the worl rl ing plunger a. by two divided rings a and a nuth. s p v Byselecting piston rodse' of relatively large 7 cross sectional area, the effectivetareas o! the 20 upper faces of the pistons e to whichthe positive injection pressure' is applied can be made smaller than those 0; the lower races rec'eiying thetpres sure for the return stroke, so'that the pistons e act as dificrentialpistons. v a j 25 'The plungers are controlled by the distributor i, the pressure medium heir 1g admitted-into the hydraulic 1 cylinder /through ,a port it tor the gdownstinke a: the working plunger, and-through a port lidr the return stroke. 'fjI'heymachine is operated in mannenw F j-By suitably setting the distributoroi, the pressuremediume s the hydraulic cylinders Z atlc, whilst theport'l is open to exhaust. In consethe tiollowinz;

quence' of the rigid connection between the two hydraulic pistons e and the working plunger 0 tinslatter' descends';lso thatxthe molten metal is injected through the nozzle/oi. the pressure .chamber' into the "mould; on the distributor i 40 being reversed, the pressure the hydraulic cylinders d'is'also reversed; the pressure thenacts on the lar'gerfaces of the'pistons e, so that the force applied to the workingplunger for the re- .turn stroke issubstanti'ally greater than that for the injection stroke. Hence, although the work ing plunger may occasionally seizedn'dts guide during the injection stage, it can be returned to its initialposition, inanycifcumstances, when the pressure is reversed for the return stroke.

The working plunger a can be replaced, in anextremely simple mannen'bynnscreening the nut h and the'dividedrings a, whereupon it can-be drawn out, at once, through' the crpsshead f, and replaced by another.

I.claim:-'- g I. In a pressure-casting appa atus of .the class described comprising a working plunger, a pressure-applying mechanism including a plurality of fluid-pressure cylinders disposed laterally with respect to "said plunger, pistons movably mounted within said cylinders, piston rods secured to said pistons, said piston rods and plunger being connected to a cross-head, the connection between the cross-head and plunger incorporating a split ring-and nut whereby the plunger may be U withdrawnthroughthe cross-head.

' a'cter described having a working plunge v, a PIES",

2. In a pressure-casting machine of the charattached to said piston'rods, a centralaperture- V in said cross-head adaptedv to receive the plunger and permit the same to, pass therethrough, a re-' duced threaded end on said plunger providing a shoulder, said shoulder being adapted to support I a split rin said split ring and a nut in threaded engagement withthe reduced end of the plunger being adapted to clamp the plunger to the cross- 3. A pressure-applying mechanism for a. pressure-casting machine having a working plunger,

, comprising "a. plurality of pressure cylinders dis plunger being disposed in said opening saidopenposed equidistant from said working plunger, sauf' pressurecylinders. and working. plunger having parallel axes, pistonswithin said-pressure cyi-f v inders, said'pistons being provided with piston rods secured to' a common cross-head, a central l5 v plunger-receiving aperture in said cross-head, 5 said aperture being adaptedto receive the workingplunger and permit the same to pass there'- through, a groove in said working plunger adapt ed to receive halves of a split'ring, said split ring 10 constituti a laterally extending shoulder for bearing "abutment against the cross-head, and a clamping nut in threaded engagement with the extreme end of the working plunger adapted to draw the split ring into clamped relationship'lb .with the cross-head i 4, In a pressure-casting apparatus of the class described comprising a working plunger, apressure-applying device including a plurality of fluidpressure cylinders disposed laterally with respect to said plunger, pistons'mounted within said cylv inders, piston rods secured to said pistons, a cross-head connectedto said piston rods, said cross-head having an opening therethrough, said 25' ing being larger than the greatest cross-section of the part of the plunger below said cross-head whereby said plunger ,isadapted to be withdrawn,

\ therethrough, and detachable means associated.

with said plunger and said cross-head for securing the plunger to the cross-head.

' ALFRED BAUER. 

